Question

You observe that a collection three loblolly pine (Pinus taeda L.) populations, one located in eastern Texas, one located in central Alabama, and one located in northern Virginia, have an observed value for F_ST at the 4CL gene of 0.457. What can you conclude about these three populations?

	A.	These three populations act as one large, randomly mating population.
	B.	These three populations are completely inbred.
	C.	These three populations are completely outbred.
	D.	There is a 45.7% reduction in the frequency of heterozygotes in the observed data relative to that expected in one large, randomly mating population.

Answer 1

Ans-These three populations are completely inbred.

FST is a method to assess how different a group of populations are from each other. This value, ranges from 0 (not different) to 1 (completely different, no alleles held in common) is a pairwise comparison of differences in allele frequency. When there are no differences in allele frequency between populations (FST=0), then either there is a high amount of gene flow between the populations equalizing the allele frequencies, or the groups sampled don’t actually represent separate groups of individuals. If an FST is 1, then no alleles are shared between populations. In reality, FST estimates between populations with no gene flow can be low (for example between 0.01-0.1), but due to a shared ancestor, the majority of alleles can be in common between populations. In these cases, the frequency of alleles common to multiple populations may differ due to the results of genetic drift or inbreeding occurring independently in each population, resulting in the random change of allele frequencies. New alleles could also be introduced through mutation, also a random and independent process. The individual pairwise comparisons of FST within a group of populations can be averaged to estimate the overall mean FST for the entire group
.